Do stats not matter to you anymore?
i perceive him to be a good rebounder, even when you discount his contribution on the boards with the knowledge that he's scarcely asked to do anything except rebound. the statistics indicate that as well. i do not perceive him to be a particularly good defender, nor are there any stats that contradict my visual assessment.
I mean, for a big man, the only statistical defensive measurements are blocks and rebounds. And statistics would indicate he's quite good at rebounding and acceptable at blocking shots. You're correct that that there are no other stats which support/refute whether a player is a good defender.
Visually, I see a guy who rebounds well, is active around the rim, changes shots, and gets to loose balls that other bigs don't get to. He's all over the f'n place. But, yeah, stats won't back a lot of this up.